Idle Control Valve P0505

[alancrobertson]

I have a fault P0505 which is the idle control valve high / low. I have replaced the idle control valve, throttle position sensor and cleaned the throttle body. None seem to have fixed the fault. When testing the wiring I noticed that I am not getting any signal to the idle control valve. I have checked the connector going into the valve and it is firmly seated but I cannot see where the other end of the cable goes without taking more of the engine apart. Does it plug straight into the ECU? If so is it a connector that may have come loose or is it hard wired in? If it is hard wired in will I need a new ECU?

Many Thanks

Alan

[Adam-D]

hmm, try pulling the battery off for a bit, then try it, see if the ecu picks it up

icv wireing is straight to the ecu in amongst all the other engine loom.

what engine, and year?

[alancrobertson]

Hello Adam,

Thanks for the reply. It is a Corsa Envoy, not sure of year but I think 1999. I disconnected the battery for half an hour and tried again and the same fault came back but now I am getting a signal to the idle valve. Thanks! I can now rule out a bad connection. If I use a battery to fully close the idle valve and switch the engine on it extends the idle valve to the maximum and then the engine management light comes back on with a fault P0505. Some more info I got from the laptop with the engine management light on:

Idling at 1400 revs
Idle Switch = Closed
Throttle Position Sensor = 1.05V
Throttle Angle = 0
EGR = Inactive

If I press the accelerator the results vary:
Revs increase
Idle Switch = Open
Throttle Position Sensor increases
Throttle Angle increases
EGR alternates between open / closed

I am now wondering if it could be blocked hose somewhere in the throttle body - perhaps not getting enough air? The throttle body appears to be clean and the "butterfly" is clean. Any ideas?

Alan